KR20120098507A - Gas manifold, module for a lithographic apparatus, lithographic apparatus and device manufacturing method - Google Patents

Abstract

A gas manifold is provided for directing gas flow between two parallel plates of an optical component of a lithographic apparatus, the gas manifold having an inlet for providing gas flow to the gas manifold, A lattice comprising a plurality of through holes for homogenization, a systole disposed downstream of the lattice to reduce the cross-sectional area through which the gas flow flows, and downstream of the systolic to provide the gas flow to the two parallel plates. And an outlet disposed therein.

Description

GAS MANIFOLD, MODULE FOR A LITHOGRAPHIC APPARATUS, LITHOGRAPHIC APPARATUS AND DEVICE MANUFACTURING METHOD}

The present invention relates to a gas manifold, a module for a lithographic apparatus, a lithographic apparatus, and a device manufacturing method.

BACKGROUND A lithographic apparatus is a machine that applies a desired pattern onto a substrate, typically onto a target portion of the substrate. The lithographic apparatus may be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterning device, alternatively referred to as a mask or a reticle, can be used to create a circuit pattern to be formed in a separate layer of the IC. This pattern can be transferred onto a target portion (eg, including a portion, one or several dies) of a substrate (eg, a silicon wafer). Transfer of the pattern is typically performed through imaging onto a layer of radiation-sensitive material (resist) provided in the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and scanning the pattern through a radiation beam in a given direction ("scanning" -direction) Called scanner, in which each target portion is irradiated by synchronously scanning the substrate in a direction parallel (parallel to the same direction) or in a reverse-parallel direction (parallel to the opposite direction). It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

In the fabrication of ICs, continued improvements in microprocessor speed, memory packing density, and low power consumption for microelectronic components have been found in the size of patterns transferred from the patterning device to the substrate by the lithographic apparatus. Requires continuous reduction However, as the size of integrated circuits decreases and the density increases, the CD (critical dimension) of the corresponding patterning device pattern has reached the resolution limit of the lithographic apparatus. The resolution for a lithographic apparatus is defined as the minimum feature that the apparatus can repeatedly expose to a substrate. In order to extend the resolution limit of the lithographic apparatus, various techniques known as resolution enhancement techniques have been applied.

One technique for improving resolution is off-axis illumination. Using this technique, the patterning device is illuminated at a selected non-vertical angle, which improves resolution and, in particular, increases process latitude by increasing depth of focus and / or contrast. It can be improved. The angular distribution in the patterning device plane, which is the object plane, corresponds to the spatial distribution in the pupil plane of the optical arrangement of the lithographic apparatus. Typically, the shape of the spatial distribution in the pupil plane is called the illumination mode. One known illumination mode is annular, in which the conventional zero order spot of the optical axis changes to a ring-shaped intensity distribution. Another mode is multipole illumination, in which several spots or beams are created that are not on the optical axis. Examples of multipole illumination modes include a dipole comprising two poles and a quadrupole comprising four poles.

For illumination modes such as dipoles and quadrupoles, the size of the poles in the pupil plane can be very small compared to the entire surface of the pupil plane. As a result, substantially all of the radiation used to expose the substrate traverses only the pupil planes at or near the various optical elements at locations where these poles are located. Fraction of radiation across one or more optical elements (eg, one or more lenses) is absorbed by the element (s). This leads to non-uniform heating of the element (s) by the radiation beam, resulting in local deformation of the element (s) and deformation of the element (s). Deformation of the element (s) and local changes in refractive index or reflectance can lead to distorted aerial images when projected by the projection system onto the substrate, for example onto the resist layer of the substrate. US Pat. No. 7,525,640, herein incorporated by reference in its entirety, provides a solution to the aforementioned problem.

A possible solution to non-uniform heating is to provide optical components, for example in the path of and transverse to the radiation beam. The optical component comprises a plate and generally a first plate having individually addressable electrical heat transfer devices configured to locally heat and / or cool the optical component. The refractive index, reflectance or deformation of the plate and / or optical component in general can be changed by changing its temperature at local locations. An additional plate parallel to the first plate may be provided, for example, as part of the optical component. Between two parallel plates a flow of gas is provided. This reduces heat transfer in the direction perpendicular to the radiation beam. If this is not the case, heat can be transferred from the high temperature locations to the low temperature locations due to the conduction which reduces the gradient of achievable refractive index, reflectance or change in deformation. As such, a gas (eg, cold gas) is used as an offset to the heat transfer device. In one embodiment, the gas is substantially at the same temperature as the optical component (which may be a predetermined temperature) (eg, 22 ° C.) so as not to interfere with the thermal equilibrium of the optical component (which may be a lens). )to be. Additionally, by providing the gas at a temperature lower than the ambient temperature, two-sided correction (ie, heating and cooling) can be obtained.

For example, it is desirable to provide a gas manifold in which several measures have been taken to stabilize the gas flow provided between at least two parallel plates of the optical component of the lithographic apparatus.

According to one embodiment of the invention, there is provided a gas manifold for directing gas flow between at least two parallel plates of an optical component of a lithographic apparatus, the gas manifold being a gas flow to the gas manifold. An inlet for providing a; A lattice made of metal and comprising a plurality of through holes for homogenizing the gas flow; A contractor disposed downstream of the lattice to reduce the cross-sectional area through which the gas flow flows; And an outlet disposed downstream of the systolic to provide the gas flow to the at least two parallel plates.

According to one embodiment of the invention, there is provided a gas manifold for directing gas flow between at least two parallel plates of an optical component of a lithographic apparatus, the gas manifold being a gas flow to the gas manifold. Inlet for providing; A grid including a plurality of through holes in a regular periodic structure to homogenize the gas flow; A constrictor disposed downstream of the lattice to reduce the cross-sectional area through which the gas flow flows; And an outlet disposed downstream of the systolic to provide the gas flow to the at least two parallel plates.

According to one embodiment of the invention, projecting a patterned beam of radiation onto a target portion of a substrate using a projection system; Locally changing the optical path length of the radiation beam using a plate disposed transversely to and in the path of the radiation beam, the plate being locally heated; And providing the gas flow through the grating made of metal and comprising a plurality of through holes to homogenize the gas flow, to the systolic and between the plate and an additional plate parallel to the plate. This is provided.

According to one embodiment of the invention, projecting a patterned beam of radiation onto a target portion of a substrate using a projection system; Locally changing the optical path length of the radiation beam using a plate disposed transversely to and in the path of the radiation beam, the plate being locally heated; And providing the gas flow through the grating comprising a plurality of through holes in a structure having a regular period to homogenize the gas flow, between the plate and an additional plate parallel to the plate. A manufacturing method is provided.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which corresponding reference numerals indicate corresponding parts.
1 shows a lithographic apparatus according to an embodiment of the present invention;
2 is a perspective view of an optical component of a lithographic apparatus comprising two parallel plates;
3 shows a gas manifold, optical component and gas flow path of an embodiment of the invention;
4 shows schematically a through hole of a grating;
5 shows temperature fluctuation values for a gas manifold with different screens;
6 shows temperature fluctuation values for a gas manifold with different combinations of gratings and inlets with walls of poly (methyl methacrylate) (PMMA);
FIG. 7 shows temperature fluctuation values for a gas manifold with two gratings, with an inlet part with walls made of PMMA, and another case with an inlet part made of steel; And
8 schematically shows projections that can be used on the wall of the inlet part or on the wall of the gas manifold.

Figure 1 schematically depicts a lithographic apparatus according to an embodiment of the invention. The device is:

An illumination system (illuminator) IL configured to condition the radiation beam B (eg UV radiation or DUV radiation or EUV radiation);

A support structure (eg mask) configured to support the patterning device (eg mask) MA and connected to a first positioner PM configured to accurately position the patterning device according to certain parameters. Table) (MT);

A substrate table (e.g., connected to a second positioner PW, configured to hold a substrate (e.g. a resist-coated wafer) W, and configured to accurately position the substrate according to certain parameters. Wafer table) (WT); And

A projection system (e.g., a projection system) configured to project a pattern imparted to the radiation beam B by a patterning device MA onto a target portion C (e.g. comprising one or more dies) For example, a refractive projection lens system (PS).

Lighting systems may be of various types, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, to direct, shape, or control radiation. It may include optical components.

The support structure MT holds the patterning device. The support structure MT holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether the patterning device is maintained in a vacuum environment. The support structure MT may utilize mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device. The support structure MT may be, for example, a frame or a table, which may be fixed or movable as required. The support structure MT can ensure that the patterning device is in a desired position, for example with respect to the projection system. Any use of the terms "reticle" or "mask" herein may be considered synonymous with the more general term "patterning device".

As used herein, the term “patterning device” should be broadly interpreted to refer to any device that can be used to impart a pattern to a cross section of a radiation beam in order to create a pattern in a target portion of a substrate. The pattern imparted to the radiation beam may not correspond exactly to the desired pattern of the target portion of the substrate, for example if the pattern comprises a phase-shifting feature or a so-called assist feature. It should be noted that there is. In general, the pattern imparted to the radiation beam will correspond to a particular functional layer of the device to be created in the target portion, such as an integrated circuit.

The patterning device can be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in the lithography field and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. One example of a programmable mirror array employs a matrix configuration of small mirrors, each of which can be individually tilted to reflect the incident radiation beam in a different direction. Inclined mirrors impart a pattern to the beam of radiation reflected by the mirror matrix.

The term "projection system" as used herein, if appropriate for the exposure radiation used, or for other factors such as the use of immersion liquid or the use of a vacuum, refracting, reflecting, catadioptric, magnetic, electromagnetic And electrostatic optical systems, or any combination thereof, should be construed broadly as encompassing any type of projection system. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system”.

As shown herein, the apparatus is of a transmissive type (e.g. employing a transmissive mask). Alternatively, the apparatus may be of a reflective type (e.g., employing a programmable mirror array of the type as mentioned above or employing a reflective mask).

The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and / or two or more patterning device tables). In such "multiple stage" machines additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more tables are being used for exposure.

Referring to FIG. 1, the illuminator IL receives a radiation beam from a radiation source SO. For example, where the source is an excimer laser, the source and the lithographic apparatus may be separate entities. In such a case, the source is not considered to form part of the lithographic apparatus and the radiation beam is, for example, with the aid of a beam delivery system (BD) comprising a suitable directing mirror and / or beam expander. From SO to the illuminator (IL). In other cases, for example, where the source is a mercury lamp, the source may be an integral part of the lithographic apparatus. The source SO and the illuminator IL may be referred to as a radiation system together with a beam delivery system BD if necessary.

The illuminator IL may comprise an adjuster AD for adjusting the angular intensity distribution of the radiation beam. In general, at least the outer and / or inner radial extent (commonly referred to as -outer and -inner, respectively) of the intensity distribution in the pupil plane of the illuminator can be adjusted. In addition, the illuminator IL may include various other components, such as an integrator (IN) and a condenser (CO). The illuminator can be used to condition the radiation beam to ensure that the cross section of the radiation beam has the desired uniformity and intensity distribution. Similar to the source SO, the illuminator IL may or may not be considered to form part of the lithographic apparatus. For example, the illuminator IL may be an integral part of the lithographic apparatus or may be a separate entity from the lithographic apparatus. In the latter case, the lithographic apparatus can be configured such that the illuminator IL can be mounted thereto. Optionally, the illuminator IL is removable and may be provided separately (eg, by the lithographic apparatus manufacturer or other supplier).

The radiation beam B is incident on the patterning device (e.g., mask) MA, which is held in the support structure (e.g., mask table) MT, and is patterned by the patterning device. If it has crossed the patterning device MA, the radiation beam B passes through the projection system PS and focuses the beam onto the target portion C of the substrate W. Substrate table WT, with the aid of a second positioner PW and a position sensor IF (eg, an interferometric device, a linear encoder, or a capacitive sensor). Can be accurately moved to position different target portions C in the path of the radiation beam B, for example. Similarly, the first positioner PM and another position sensor (not clearly shown in FIG. 1) can be used for example after mechanical retrieval from a mask library or during scanning. It can be used to accurately position the patterning device MA with respect to the path of the beam B. In general, the movement of the support structure MT may be realized with the aid of a long-stroke module and a short-stroke module, 1 positioner PM. Similarly, the movement of the substrate table WT can be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the support structure MT may be connected or fixed only to the short-stroke actuators. The patterning device MA and the substrate W may be aligned using patterning device alignment marks M1 and M2 and substrate alignment marks P1 and P2. Although the substrate alignment marks illustrated occupy dedicated target portions, they may be located in the spaces between the target portions (these are known as scribe-lane alignment marks). Similarly, in situations where the patterning device MA is provided with one or more dies, the patterning device alignment marks may be located between the dies.

The device shown may be used in at least one of the following modes:

1. In the step mode, the support structure MT and the substrate table WT remain essentially stationary, while the entire pattern imparted to the radiation beam is projected onto the target portion C at once (ie, a single static Single static exposure]. Thereafter, the substrate table WT is shifted in the X and / or Y direction so that different target portions C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged during a single static exposure.

2. In scan mode, the support structure MT and the substrate table WT are scanned synchronously while the pattern imparted to the radiation beam is projected onto the target portion C (ie, single dynamic exposure). )]. The speed and direction of the substrate table WT relative to the support structure MT may be determined by the magnification (image reduction) and image reversal characteristics of the projection system PS. In the scan mode, the maximum size of the exposure field limits the width (in the unscanned direction) of the target portion during a single dynamic exposure, while the length of the scanning operation determines the height (in the scanning direction) of the target portion.

3. In another mode, the support structure MT remains essentially stationary by holding the programmable patterning device and the substrate table WT while the pattern imparted to the radiation beam is projected onto the target portion C. ) Is moved or scanned. In this mode, a pulsed radiation source is generally employed, and the programmable patterning device is updated as needed after each movement of the substrate table WT, or between successive radiation pulses during a scan . This mode of operation can be readily applied to maskless lithography using a programmable patterning device, such as a programmable mirror array of a type as mentioned above.

Combinations and / or variations on the above described modes of use, or entirely different modes of use, may also be employed.

The intensity distribution of the radiation beam may comprise a plurality of poles that define a portion of the cross section of the pupil plane, through which substantially all radiation of the radiation beam crosses the pupil plane. In the following description, the intensity distribution of the radiation beam in the pupil plane is referred to as the illumination mode. In one embodiment, the intensity distribution is a dipole illumination mode (two poles). In one embodiment, the intensity distribution is a quadrupole illumination mode (four poles).

When the radiation beam crosses a refractive optical element (eg a lens) or a reflective optical element (eg a mirror), a small portion of the radiation beam is absorbed by the element. Absorption of the radiation beam by the element heats the element. Heating of the element changes the refractive index or reflectance of the element at the absorption position and induces deformation of the element. For an element located at a position where the beam of radiation is uniformly across the element, this absorption leads to uniform heating of the element and a uniform change in refractive index or reflectance and deformation. This may be particularly detrimental to non-parallel elements (eg convex or concave elements). For an element located at or near the pupil plane, the cross-sectional portion of the element through which the radiation beam traverses the element depends on the illumination mode in which it is applied. For illumination modes such as dipoles or quadrupoles, the element absorbs radiation non-uniformly across the element surface, causing non-uniform changes in the refractive index or reflectance and deformation of the element. Local changes in refractive index or reflectance and deformation of one or more elements of the projection system can lead to changes in the optical path length of different portions of the radiation beam across the elements. The variations in the optical path lengths are due to the difference in the optical path lengths between the parts of the radiation beam to be recombined, resulting in an aerial image at the substrate level where the parts of the radiation beam are distorted relative to the object image at the patterning device level. To be recombined. One example of an imaging parameter negatively affected by this difference is a field position dependent focus offset. Although the specification focuses on the transmission optical elements and the refractive index, embodiments of the present disclosure may also be appropriately applied to reflective optical elements. For example, the radiation may be reflected by one or more plates described later, rather than passing through one or more plates described later.

2 shows one embodiment of an optical component 50 comprising at least two parallel plates 52, 54. At least one parallel plate 52 comprises electrical heat transfer devices 53 (eg, heating devices in the form of meandered conductors comprising a conductor, for example parallel filaments). . The electrical heat transfer devices 53 are electrically connected to the control unit 80 and are separated from each other. The control unit 80 utilizes a known time multiplexing addressing technique to generate the amount of heat transfer required for the associated portions of the optical element, each of the electrical heat transfer devices (9 shown). Address the electrical heat transfer device. Optical component 50 may include any number of electrical heat transfer devices. By this, the optical component 50 allows the creation of warmer and cooler regions locally in the cross section of the projection beam PB. This capability can be used to offset lens heating elsewhere by offsetting the heating of the optical element (eg lens) (generally referred to herein as lens heating). Lens heating may be due to, for example, the passage of the projection beam PB through the local area of the lens. Additionally or alternatively, this capability can be used to correct lens life effects and / or image enhancement techniques.

The heat transfer into the optical component 50 in the direction perpendicular to the radiation beam PB is preferably minimized. To this end, the channel 66 defined by the plates 52 and 54 generates heat transfer in the optical component 50 in a direction substantially parallel to the radiation beam PB as indicated by arrow 68. Is arranged to. This is indicated by the arrow 67 with a fluid, for example an [ultra-high-purity] gas, such as a non-reactive gas, such as a gas substantially comprising N ₂ or He. As shown, this is accomplished by guiding through the channel 66 from the supply. In one embodiment, the gas is maintained at a lower temperature than the optical component 50. Typically, the channel 66 will have dimensions comparable to the size of the optical component 50 in the X and Y directions, and typically less than 12 mm or 10 mm in the Z-direction, typically about 7 mm. It will have a height of mm. The temperature of the gas can be maintained substantially constant using a known temperature control device disposed between the gas supply 14 (shown in FIG. 3) and the optical component. The gas may be reused by operating a circulation loop in which the gas returns to the gas supply 14 after passing through the optical component.

In order to enable bilateral correction and to keep the optical component at a predetermined average temperature throughout (which can be preset), a heat transfer (eg, cooling) power bias is employed. Used. It is supplied by a (ultra-high-purity) gas flow of several hundreds of liters per minute (for example, when XCDA is used; lower flow rates may be used when He is used). . The gas flow may have a cooling function. Gas is supplied through the gas manifold 10 illustrated in FIG. 3. Gas is provided to the gas manifold 10 through the inlet 12. Gas is provided from the gas supply 14 to the inlet. The speed of the gas in the hose between the gas supply 14 and the inlet 12 is limited to a certain acceptable upper limit.

Turbulence of gas flow between at least two parallel plates 52, 54 may be detrimental to wavefront stability and thus the function of optical component 50. One embodiment of the present invention discloses an improvement in the gas manifold disclosed in US patent application US 61 / 394,444, filed October 19, 2010, which is incorporated herein by reference in its entirety. Portions of the gas manifold of US patent application US 61 / 394,444 are illustrated in FIG. 3. The gas manifold 10 includes a diffuser 16 downstream of the inlet 12. The diffuser 16 may be in any form that provides a pressure drop, for example by providing a plurality of through holes, such as a porous (metal) plate, to provide a pressure drop (of a several bar). It may be a member having. This helps to keep the upstream pressure high, allowing a lower gas velocity at higher pressure from the gas supply 14. In addition, diffuser 16 leaves the diffuser 16 on the downstream side to induce a substantially uniform gas flow rate across the cross-sectional area.

Downstream of the diffuser 16 is a flow straightener 18. The flow direct current 18 straightens the flow of the gas so that the gases all flow in substantially parallel directions. Flow direct current 18 attenuates fluctuations perpendicular to the flow direction. The flow direct current 18 improves performance by reducing the magnitude or occurrence of spanwise temperature modulation by reducing turbulence. The flow direct current machine 18 includes a plurality of passages for gas flow therethrough. In one embodiment, the flow direct current 18 has an open area ratio (ratio of passage to material in section) of at least 0.5, preferably greater than 0.55, or even greater than 0.6. In one embodiment, the flow direct current is a honeycomb flow direct current. For honeycomb flow direct current motors, the aperture ratio is typically 0.5 to 0.6 and has a relatively small hole diameter. The optimum length L of the flow direct current 18 passage with respect to the hydraulic diameter D of the passages is typically 5-15, preferably 8-12. The hydraulic diameter (calculated as four times the cross sectional area of the passage divided by the perimeter length of the passage) is 0.5 to 1.5 mm. The honeycomb flow direct current machine has passages with a hexagonal cross section.

Downstream of the flow direct current machine 18 is a shrinker 20. The systolic machine 20 thereby reduces the intensity of the turbulent flow of the gas flow. This leads to an increase in the velocity of the gas due to a phenomenon known as vortex tube stretching and so that the relative velocity fluctuations are lowered. Vortex tube stretching leads to faster decay of larger flow structures. The cross sectional area of the constrictor 20 through which the gas flow flows becomes smaller downstream. This reduces the intensity of turbulence in the gas flow.

In one embodiment, the systolic 20 is a planar systolic. In other words, contraction occurs only in one direction (z direction) and there is no contraction in the orthogonal direction perpendicular to the flow direction (x direction as illustrated). This means that the size of the systolic 20 in the z-direction is further reduced downstream. The magnitude in the x-direction does not change. Planar systolic 20 has the advantage of taking up less space than 3-D systolic. In one embodiment, systolic 20 may also contract in the x direction (ie, may be a 3-D systolic).

Downstream of the outlet of the systole 20 an inlet portion 22 (which may be a separate component from the manifold 10) is provided. In one embodiment, the inlet portion 22 has a substantially constant cross-sectional shape. In one embodiment, the inlet portion 22 has upper and lower plates that converge (in the z-axis) to help stabilize the flow further.

Outlet 24 is provided at the end of diffuser 16, flow direct current 18, systolic 20, and inlet portion 22 downstream of inlet portion 22. Outlet 24 is connected to optical component 50. Thereafter, gas flow passes into channel 66.

In general, a shrinkage ratio of 4 to 6 (ratio of cross-sectional areas of the inlet side of the constrictor 20 to the cross-sectional area of the outlet side of the constrictor 20) may be provided. This can lead to the largest reduction in turbulence for at least axisymmetric contraction. However, the planar shrinkage of the gas manifold of FIG. 3 may better perform at a shrinkage ratio of 1.5 to 3, or 2 to 3.

Nevertheless, turbulence may still exist for very high flow rates, and flow instability, eg Klebanoff modes, may still be excited. Such instabilities can result in stream-wise oriented optical phase streak (span-wise optical path length modulation) in the optical domain. This may cause functional limitations of the optical component 50. The presence of the stripes may be due to the widthwise temperature modulation present in the gas flow. This modulation is due to vortex streaks developing in the gas close to the walls of the gas manifold 10 that define the flow path of the gas flow through the gas manifold. This results in non-uniform heat pickup in the walls.

When the Reynolds number (Re) is in the transition or low-turbulent phase (Re is between 4,000 and 6,000), and the level of disturbance is large enough to cause streaks and grow. Only when not large enough to cause breakage of coherent structures, the formation of streaks can occur in this flow type. However, the boundary conditions and heat transfer capacity requirements of the gas manifold 10 (eg, cooling capacity requirements) are the geometry that induces this transition or low-turbulent Reynolds number when air or similar gas is used as the heat transfer medium. And dictate the flow speed. Additional measures may be taken on the gas manifold 10 to address this problem as described below.

US patent application US 61 / 394,444 discloses several measures that can be taken at the inlet portion 22 to cope with optical phase stripes oriented in the flow direction. One embodiment of the present invention may be used in addition to or instead of these measures.

One embodiment of the present invention is directed to at least one lattice, grid, or screen 200a, 200b, 200c located upstream of the systolic 20. In the embodiment of FIG. 3, the grating is located downstream of the flow direct current 18. However, in one embodiment at least one grating 200a, 200b, 200c may be located upstream of the flow direct current 18 (and downstream of the diffuser 16). In one embodiment, the grating 200 is located downstream of the flow direct current machine 18. This is because the flow direct current 18 may introduce inhomogeneities (eg, minor turbulence, eg, vortex shedding) into the flow, and the grating 200 is reduced or Intended to be removed. However, the aggregate effect of the direct current machine 18 is positive. Also, the grating (s) downstream of the direct current machine may eliminate or reduce turbulence, but / or they do more. In addition to eliminating turbulence, the grating (s) lower the turbulence level of the overall flow even further.

At least one grating 200a, 200b, 200c promotes flow uniformity and reduces turbulence.

US patent application US 61 / 394,444 suggests that one or more permeable membranes made of fabric may spanned over the flow region upstream or downstream (or both) of flow direct current machine 18. . Wherein one or more gratings are similar to the fabric. The gratings 200a, 200b, 200c may include a plurality of regularly spaced through holes, promoting homogenization of the gas flow. In other words, the through holes have a structure having a regular (two-dimensional) period. This structure promotes flow uniformity and reduces turbulence. In one embodiment, the grating is rigid such that a structure with regular periods is maintained. The lattice has structural integrity so that regularity is not broken in treating the lattice for manufacture and / or cleaning.

In one embodiment, the gratings may be made of metal. As illustrated below, this leads to an improved removal of the optical phase stripes oriented in the flow direction. This is partly due to the high aperture ratio compared to cloth screens. In addition, the advantages of metals are that they are more washable, more durable, and with higher thermal conductivity, so that the metal helps the temperature more evenly. Another advantage of the metal grating is that temperature conduction through the metal grating helps to reduce temperature fluctuations between the walls of the manifold.

Experiments with various different gratings showed variations in the removal performance of the optical phase stripes oriented in the flow direction. 4 schematically illustrates a through hole 210 of a grating having a structure having a regular period such that the through holes 210 are regularly spaced and / or periodically spaced. The dimensions of the grid include the height H of the through hole 210, the width W of the through hole 210, and the dimension D of the material (eg, filament) defining the through hole 210. do.

The table below shows the dimensions D, H and W for a plurality of different gratings L1 to L8 and includes the calculated A _ratio for each grating. The aperture ratio is defined as the area of the opening divided by the total area. Mesh size (typically measured in filaments per inch) can be defined from these dimensions and is given as being the through-hole hydraulic diameter (D _H / D) relative to the filament diameter ( Assume a round line). The gratings L3 and L4 have irregular weaves, the gratings L1 to L4 are woven gratings, and the gratings L5 to L8 are metal gratings with regular weaves. In particular, the grids of L5, L6, L7 and L8 are made of austenitic steel and have a structure with regular periods.

The characteristics of the gratings are shown below.

FIG. 5 shows experimental results of gas temperature variations for a gas manifold set up as in FIG. 3 using different gratings. The graph shows the change in temperature (on the vertical axis) with the position (on the horizontal axis). The temperature at the top wall of the outlet side 24 of the inlet portion 22 is shown. Results are plotted for the case where the grating is not in place and for the measurements made for each single grating of L1, L2, L6, L7 and L8. It is not expected that gratings of irregular weave will function well.

From FIG. 5, the temperature fluctuations in the middle region (in the X direction) of the outlet side 24 (ie, the region excluding the outer edges whose temperature profile is affected by contact with the side walls of the gas manifold) ( It is possible to determine dT).

These results show that optimal performance is achieved with the lattice L7 and L8. This is considered to be due to their high aperture ratio (0.37 or more). Even better performance is achieved with an aperture ratio of 0.4 or more.

As can be seen, the higher the aperture ratio, the better the performance. In theory, the optimum optical ratio is 0.58. However, this can be difficult to achieve in practice. Therefore, an aperture ratio of 0.37 or more is used. If the aperture ratio is too low, this can cause turbulence as the jets of gas exiting adjacent through holes can interact. Therefore, in one embodiment the aperture ratio is below 0.7, or preferably below 0.6. If the aperture ratio is too high, the grating will not perform its main functions, flow homogenization and turbulence reduction. The interaction of jets is also a problem with irregular grids.

In one embodiment, the thermal conductivity of the grating material is at least 10 W / m / K, preferably at least 20 or 25 W / m / K. This helps to reduce thermal spatial variation.

Suitable materials for the grating 200 include aluminum and aluminum alloys, austenitic steels (eg, 304 or 316), crystal quartz, with a shield for sulphur content. Ferrite, NBK 7 (silica), PTFE, polycarbonate (UV shield), S-LAH 52 (silica) and / or zerodur glass ceramics. Of course, the most stiffest ones and materials with high thermal conductivity (ie, metals) are preferred.

Any way of making the grating is possible. For example, the grating may be two filament layers lying across one another using some way of attaching the layers together only to provide the necessary rigidity. The grating may be, for example, a single component using three-dimensional printing.

Lattice L6, having an aperture ratio comparable to that of L7 and L8, is not considered to function as L7 and L8, in part because it has a small mesh size (i.e., through holes are too large) This is because it may not be effective to homogenize uniformity and reduce turbulence (reduce flow oscillation in the flow direction).

In the case of a square through hole, the hydraulic diameter D _H can be estimated as the width of the through hole. Hydraulic diameters of 70 μm or more are preferred. A suitable ratio of through hole hydraulic diameter D _H to the filament diameter of the grating is at least 1.0, at least 1.4, at least 1.8, or at least 2.0.

As illustrated in FIG. 3, one or more gratings 200a, 200b, 200c may be used. Multiple gratings are arranged in series. FIG. 6 shows the results for different configurations of multiple gratings in a graph similar to FIG. 5. The results below show improved performance using multiple gratings (see, for example, two screens L7-L7 that show improvement over a single L7). Three L7 gratings do not exhibit improved performance over two L7 gratings. By using two gratings with the highest available aperture ratio and the ratio of the highest through hole hydraulic diameter to the filament diameter, optimal performance can be achieved.

Too many gratings are not very helpful as they increase the likelihood of manufacturing error. Two to three gratings, perhaps five, are the maximum possible.

In order to create pressure drop, homogenize flow, and reduce turbulence, it is desirable to use a number of less restrictive gratings than to use one more restrictive grating. If more gratings are used, the aperture ratio of these gratings may be different. In this case, an optimal configuration can be achieved by stacking the gratings from the most restrictive to the least restrictive, i.e. from the low aperture ratio to the high aperture ratio.

The gratings are tautly mounted so as not to interfere with the (formed) boundary layer.

이며, 여기서 A는 유동 단면적이고, P는 유동 채널 둘레(flow channel perimeter)이다. (가스 매니폴드에서와 마찬가지로) 슬릿 유동에 대해, 수력 직경은 D _h = 2h에 의해 추정될 수 있으며, 여기서 h는 채널 높이이다. 수력 직경에 대한 제 1 수학식을 이용하면, D _h = 25 [mm]임에 따라, 가스 매니폴드의 통상적인 치수에 대해 거리(x)는 5 mm이다.In one embodiment, a certain distance exists between the gratings 200a, 200b, 200c, and also between the flow direct current 18 and the first grating 200a, and between the last grating 200c and the systolic 20. do. This predetermined distance x can be calculated as follows: x = 0.2D _h , where D _h is the hydraulic diameter of the flow channel,

Where A is the flow cross section and P is the flow channel perimeter. For slit flow (as in gas manifolds), the hydraulic diameter can be estimated by D _h = 2h, where h is the channel height. Using the first equation for hydraulic diameter, with D _h = 25 [mm], the distance x is 5 mm for the typical dimensions of the gas manifold.

7 shows the temperature profile for the same gas manifold and the same grating L8-L8 when the inlet portion 22 is a PMMA wall and in another case where the inlet portion 22 is a steel wall. As can be seen, the steel inlet portion induces a slightly less parabolic nature with respect to the temperature profile, which may be desirable in some embodiments.

The table below shows the top, center, and at the outlet side of the channel 22 for the best performing lattice combination with another L8 grating followed by the PMMA wall and the L8 grating of the inlet portion. It gives a temperature deviation from the perfect parabolic curve for the gas at the bottom.

As can be seen, the central trace has a variation of ± 0.07 from the sixth order parabolic fit for the data. Thus, the temperature profile can be shown to be very gentle, which is desirable; Moderate temperature fluctuations can be dealt with.

One approach disclosed in US patent application US 61 / 394,444, which addresses the problem of the presence of stripes, is to remove the disturbances generated in the systole 20. This is achieved, for example, by providing the opening 100 on the outlet side of the systolic 20. Underpressure is applied to the opening 100 by an underpressure source 102. The underpressure promotes the removal of the boundary layer of gas from the wall of the gas manifold 10, in particular the wall of the systolic 20. Alternatively or additionally, opening 100 may be provided on the wall of inlet portion 22 or on the outlet side of inlet portion 22. At either location of the inlet portion 22, the opening 100 will continue to delay the disturbance amplification, thus helping to prevent or reduce fringe formation. In addition, the underpressure may be applied upstream of the systolic 20, in the middle of the systolic 20, or any other position, or a combination of these positions.

The opening 100 may be configured in the form of a plurality of holes or slits that extend across the width of the gas manifold (eg, in a direction perpendicular to the gas flow direction). In one embodiment, the opening 100 is configured in the form of slits and has a uniform width.

In one embodiment, suction of several hundred pascals, for example on the order of 200 to 1,000 pascals, is generated by the underpressure source 102 connected to the opening 100. This removes the boundary layer formed at the end of the systolic 20, so that the disturbances may produce a stripe at the end of the inlet portion 22, at the end of the systolic 20, or at another upstream. It is effective to remove the disturbances generated in 10).

In one embodiment, the underpressure along the length of the slit-shaped opening 100 is uniform. The gas flow rate through the opening 100 is in the region of several percent of flow through the gas manifold 10, for example 1 to 10%.

In one embodiment, a portion of the wall defining the gas flow path, for example a portion of the wall of the constrictor 20 and / or the inlet portion 22, may be provided as the porous wall 110. The underpressure source 112 may apply an underpressure to the side of the porous wall 110 as opposed to the gas flow. The underpressure created by the porous wall has a stabilizing effect on the boundary layer of the gas flow. This may help to reduce or even prevent the formation of streaks. Porous wall 110 may be provided at one or more discrete locations both along the length of systolic 20 and / or inlet portion 22 or on one or both sides of the flow path.

The porous wall 110 may be made of a porous member or a member having an array of holes therein. Hole diameters of 400 μm or less, for example 200 μm (or less) and / or 4 mm or less or 2 mm (or less) pitch may be suitable. Further information on the use of porous walls can be found in: D.G. MacManus and J. A. Eaton, "Measurements and analysis of the flow field induced by suction perforations", J. Fluid Mech., Vol. 417, p. 47-75 (2000); J. Goldsmith, "Critical laminar suction parameters for suction into an isolated hole or a single row of holes" Northrop Aircraft Report no BLC-95 (1957); And D.G. MacManus and J. A. Eaton, "Flow physics of discrete boundary layer suction-measurements and predictions" J. Fluid Mech., Vol. 417, p. 47-75 (2000), each of which is incorporated herein by reference in its entirety.

In one embodiment, a sensor 114 is provided that senses a streamwise shear stress in or adjacent to the porous wall 110. The controller 116 can use this information to control the underpressure source 112 (eg, by switching one or more valves) (eg, in a feedback or feedforward manner). In this active control embodiment (which may include the occurrence of overpressure), optical fringe control can be achieved. Examples of sensors and systems incorporating such sensors are: A Elofsson, M Kawakami, P H Alfredsson, "Experiments on the stability of streamwise streaks in plane Poiseuille flow", Physics of Fluids, Vol. 11, No. 4 (1999); And F Lundell, Ph Alfredsson, "Experiments on control of streamwise streaks", European Journal of Mechanics B / Fluids, Vol. 22, pp. 279-290 (2003), each of which is incorporated herein by reference in its entirety.

In one embodiment, the gas manifold 10 and / or the inlet portion 22 are configured to introduce disturbances to the gas via vibration. In this way, dynamic equilibrium can be achieved, and the formation of streaks can be suppressed and / or prevented. In one embodiment, the vibration is introduced in a passive manner, and in another embodiment the vibration is induced in an active manner.

In an embodiment in which vibration is introduced in a passive manner, one or more walls (or a portion of one or more walls) defining the gas flow path, for example, the wall of the constrictor 20 and / or the inlet portion 22 is (rigid) Made of flexible or compliant material). The use of flexible or compliant materials is: PW Carpenter, C. Davies and AD Lucey, "Hydrodynamics and compliant walls", CURRENT SCIENCE, VOL. 79, NO. 6 (September 25, 2000); And J. Hoepffner, A. Bottaro and J. Favier, "Mechanisms of non-modal energy amplification in channel flow between compliant walls", Journal of Fluid Mechanics (2009), each of which is incorporated herein in its entirety. Reference is made. Wall vibrations are generated by the flow of gas through the walls. Vibration introduces additional disturbances into the boundary layer that can disrupt the processing of the waveform amplification, which ultimately results in the formation of stripes. Alternatively, the flexible walls can be configured to effectively attenuate the disturbances present in the boundary layer before the disturbances cause striation. In one embodiment, the flexible wall is a polymeric material, such as rubber (e.g. latex, silicone, etc.), fluoroelastomers such as Viton fluoroelastomers, fluoros such as PFA fluorocarbon resins. Carbon resins, polytetrafluoroethylene such as Teflon polytetrafluoroethylene, styrene-butadiene rubber, composites and the like. The stiffness of the walls is chosen such that the flow of gas in the manifold induces the formation of vibrations. Carpenter, "Instabilities in a plane channel flow between compliant walls", JFM, 1997, parts I and II, herein incorporated by reference in its entirety, discloses how wall robustness should be selected. Spring robustness of about 1 x 10 ^-4 to 1 x 10 ^-3 N / m ³ , flexural rigidity of about 1 x 10 ^-5 to 1 x 10 ^-4 Nm, and 1 x 10 ^-3 to 2 x Area densities of 10 ⁻² kg / m ² are common.

In an active embodiment, an actuator 120 may be provided to induce vibration in the z direction on the wall, or a portion of the wall or two walls in the x-y plane. Wall vibrations can have a significant impact on flow behavior, especially in the transition range of the boundary layer. See, for example, M R Jovanovic, "Turbulence suppression in channel flows by small amplitude transverse wall oscillations" Phys Fluids 20, 014101 (2008), which is incorporated herein by reference in its entirety. The actuator must be configured to satisfy the following equation:

W = 2 α sin ( ωt )

10 내지 20 Hz 또는 15 Hz임을 의미한다. 동시에, 진동의 진폭은 유입 유동 속도의 약 2 내지 5 %(또는 다시 말해, α

유동 속력의 0.01 내지 0.025 배)이어야 한다.Where W is the wall velocity, α is the amplitude scaling factor, and ω is the frequency. For optimal disturbance control, ω should be chosen such that ω = Ω * v / δ ² , v is the kinematic viscosity of the gas, and Ω is the frequency scaling factor, which is about 17.6 is equal to half the channel width. In one embodiment, it is ω

It means 10 to 20 Hz or 15 Hz. At the same time, the amplitude of the oscillation is about 2-5% of the inflow flow rate (or in other words, α

0.01 to 0.025 times the flow speed).

In one embodiment, a plurality of plurality of elongate projections is provided on the wall of the gas manifold 10 that defines the flow path for gas flow. For example, a plurality of elongate recesses and protrusions may be provided in the walls of the constrictor 20 and / or the inlet portion 22. If a plurality of elongate irregularities are formed, the plurality of elongate irregularities stop the formation of stripes or reduce their coherence. This does not introduce excessive additional turbulence or significantly affect the heat transfer capacity. 8 schematically illustrates a plurality of irregularities formed in one or both walls of a gas manifold or inlet portion 22. The walls of the inlet portion 22 are spaced apart by a distance D.

The uneven portions are elongated in the gas flow direction. In cross section, the uneven parts have a triangular shape. However, any shape can be used. The presence of the uneven portions weakens the flowwise vortices, thus inhibiting the formation of widthwise temperature modulation. This occurs due to the effect of secondary vortices at the uneven ends. If the height of the uneven portion h (for example, the amount of uneven portion protruding into the flow path) is 0.2 to 1.0 mm and the pitch s between the uneven portions is 0.5 to 2.0 mm, the movement of the secondary vortices is in the flow direction Effectively weakens the vortex and prevents its own amplification. This is referred to in S.J. Lee and S.H. Lee, "Flow Field Analysis of a Turbulent Boundary Layer Over a Riblet Surface", Exp in Fluids 30, 153-166 (2001).

1 mm 및 h

0.5 mm의 요철부 지오메트리를 산출한다. Typical optimal values can be realized for the riblet spacing s + = suτ / v, which is comprised between 10 and 20, and h between 0.5s and 1s. In the definition of s +, v is the dynamic viscosity of the gas and uτ is the shear velocity. The latter is defined as (τw / ρ) 0.5, where τw is the shear stress on the wall and ρ is the gas density. For gas manifold 10, this is about s

1 mm and h

The uneven part geometry of 0.5 mm is calculated.

When the uneven portions are relatively small (for example, s = 1 mm and h = 0.5 mm), suppression of the widthwise temperature modulation can be achieved. Larger concavities and convexities (eg s = 2 mm and h = 1 mm) tend to introduce their overlapping profile. Typically, s can be between 0.5 and 2.0 mm and h can be between 0.25 and 1 mm.

4000 내지 6000 주위에서 가장 강하다.As described above, the formation of stripes that induce phase ripple (ie, width modulation in the optical phase) has a specific range of Reynolds number, [for plane Poiseuille flows] Re.

Strongest around 4000 to 6000.

Creating the desired heat transfer capacity with air requires a large flow rate, which leads to the transition and low-turbulent Reynolds numbers mentioned previously. Different gases with higher thermal conductivity may be used to enable a reduction in flow velocity for the same heat transfer capacity, for example cooling capacity. The two most likely candidates for this property are helium and hydrogen, of which hydrogen may be excluded based on other properties.

Calculations using some adaptation of the Gnielinski equation yielded a linear or near linear relationship between the Reynolds number and the Nusselt number. Here, due to its apparent presence in the calculation of the Nusselt number using the Gnielinsky equations, the difference in the Prandtl number is only about 5%, so consider the enormous differences in the different gas characteristics. Note, however, that this can be ignored in first-order approximation. Thus, there is a slight linear relationship between the convective heat transfer coefficient and the Reynolds number, and moreover the mass flow accordingly (assuming much larger differences in other properties, about Ignore the difference in dynamic viscosity of 10%):

은 질량 흐름률(mass flow rate)이며, A는 유동 면적이다.Where ρ is the fluid density, V is the speed, D _h is the hydraulic diameter, μ is the dynamic viscosity, v is the kinematic viscosity,

Is the mass flow rate and A is the flow area.

The thermal conductivity of helium is about six times higher than air thermal conductivity, which means that the heat transfer capacity is increased by this same six times. This can be inferred by recalling that the Nusselt number Nu is the ratio between convection and conduction heat transfer:

Where h is the convective heat transfer coefficient, k is the thermal conductivity of the medium, and L is the characteristic length. Clearly, convective heat transfer of optical component 50 increases linearly with respect to thermal conductivity for the same Nusselt number.

Using helium instead of air allows for a significant reduction in mass flow rate (or equivalently Reynolds number), while still meeting the heat transfer capacity requirements for unchanged channel geometry [more than five times the specific heat of helium Helium's 5 times higher specific heat capacity compensates for increased heat pick-up per gram of medium]. Accordingly, the flow regime should be much more stable and show much less instability. As a result, the widthwise temperature modulation is made with a much smaller amplitude. Also, due to the fact that the temperature dependence of helium's refractive index is much lower than that of air, any temperature ripple will turn into a much lower optical phase pulsation.

The disadvantage is the cost associated with helium, and in order to solve this problem, the supply system must be a recycling system. US patent application US 61 / 394,444 gives a very basic overview of such a system.

As will be appreciated, any of the features described above may be used in conjunction with any other features, and is not limited to only those combinations explicitly described herein.

In this specification, although reference is made to a specific use of the lithographic apparatus in IC fabrication, the lithographic apparatus described herein includes integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid crystals. It should be understood that there may be other applications for manufacturing components having microscale or even nanoscale features, such as the manufacture of displays (LCDs), thin film magnetic heads, and the like. Those skilled in the art will recognize that any use of the terms "wafer" or "die" herein may be considered as synonymous with the more general terms "substrate" or "target portion", respectively, in connection with this alternative application I will understand. The substrate referred to herein may be processed before or after exposure, for example in a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool, and / or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, as the substrate may be processed more than once, for example to produce a multilayer IC, the term substrate as used herein may also refer to a substrate that already contains multiple processed layers.

As used herein, the terms “radiation” and “beam” refer to g-lines and h-lines (eg, having wavelengths of about 436 nm and 405 nm), as well as (eg, 365, 248, Encompasses all forms of electromagnetic radiation, including ultraviolet (UV) radiation, having a wavelength of 193, 157 or 126 nm, or the like.

The term "lens", where the context allows, may refer to any one or combination of various types of optical components, including refractive and reflective optical components.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, embodiments of the present invention may include a computer program comprising one or more sequences of machine-readable instructions for implementing a method as disclosed above, or a data storage medium (eg, a semiconductor) in which such computer program is stored. Memory, magnetic or optical disk). In addition, machine-readable instructions may be implemented in two or more computer programs. Two or more computer programs may be stored in one or more different memories and / or data storage media.

The controllers described above can have any configuration suitable for receiving, processing and sending signals. For example, each controller may include one or more processors that execute computer programs containing machine-readable instructions for the methods described above. In addition, the controllers may include a data storage medium that stores such computer programs, and / or hardware that receives such a medium.

One or more embodiments of the invention can be applied to any of the immersion lithography apparatus, in particular but not exclusively, the types mentioned above, wherein the immersion liquid is provided only in the localized surface area of the substrate in the form of a bath. Whether or not limited to the substrate and / or the substrate table, it may be applied to the immersion lithography apparatus of the aforementioned type. In a non-limiting configuration, the immersion liquid can flow on the surface of the substrate and / or substrate table such that substantially the entire uncovered surface of the substrate and / or substrate table is wet. In this non-limiting immersion system, the liquid supply system may not limit the immersion liquid, or may limit a portion of the immersion liquid, but may not substantially completely limit the immersion liquid.

The foregoing description is for illustrative purposes only and is not intended to be limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

1. A gas manifold for directing gas flow between at least two parallel plates of an optical component of a lithographic apparatus, the gas manifold comprising: an inlet for providing gas flow to the gas manifold; A lattice made of metal and comprising a plurality of through holes to homogenize the gas flow; A constrictor disposed downstream of the lattice to reduce the cross-sectional area through which the gas flow flows; And an outlet disposed downstream of the systolic to provide the gas flow to the at least two parallel plates.

2. In the gas manifold of 1, the through holes of the grating are regularly spaced.

3. In the gas manifold of 1 or 2, the lattice has a regular weave.

4. In a gas manifold for directing gas flow between at least two parallel plates of an optical component of a lithographic apparatus, the gas manifold comprises an inlet for providing gas flow to the gas manifold; A lattice including a plurality of through holes in a structure having a regular period to homogenize the gas flow; A constrictor disposed downstream of the lattice to reduce the cross-sectional area through which the gas flow flows; And an outlet disposed downstream of the systolic to provide the gas flow to the at least two parallel plates.

5. In the gas manifold of 4, the lattice is rigid.

6. In the gas manifold of 4 or 5, the grating has structural integrity so that regularity is not broken by the treatment of the grating.

7. In the gas manifold of any of the above 1 to 6, the aperture ratio of the grating is at least 0.37, or at least 0.4.

8. In the gas manifold of any of the above 1 to 7, the aperture ratio of the lattice is 0.7 or less, or 0.6 or less.

9. The gas manifold of any one of the above 1 to 8, wherein the through holes have a hydraulic diameter ratio to a filament diameter of at least 1.0, at least 1.4, or at least 1.8.

10. The gas manifold of any one of 1 to 9 above, wherein the through holes have a hydraulic diameter of 70 μm or more.

11. The gas manifold of any of the above 1 to 10, wherein the grating has a thermal conductivity of at least 10 W / m / K, or at least 20 or 25 W / m / K.

12. The gas manifold of any one of 1 to 11 above, wherein the grating comprises austenitic steel, aluminum, aluminum alloy, quartz, ferrite, silica, PTFE, polycarbonate, or glass ceramic.

13. The gas manifold of any one of 1 to 12 above, wherein the grating has a mesh size (filament / inch) (about 6300 to 9840 filaments / m) of 160 to 150 inch ⁻¹ .

14. The gas manifold of any one of 1 to 13, wherein the grating comprises at least two gratings positioned in line.

15. In the gas manifold of 14, the aperture ratio of any downstream lattice is at least as high as the aperture ratio of any upstream lattice.

16. In the gas manifold of 14 or 15, the distance between adjacent gratings is at least 0.2 times the hydraulic diameter of the gas manifold in the gratings.

17. The gas manifold of any one of 1 to 16, wherein the distance between the grating and adjacent components of the flow path of the gas in the gas manifold is at least 0.2 times the hydraulic diameter of the gas manifold in the grating.

18. The gas manifold of any one of 1 to 17, further comprising a flow direct current downstream of the inlet to straighten the flow of the gas.

19. The gas manifold of 18, wherein the flow direct current is disposed upstream of the at least one grating.

20. In the gas manifold of 18 or 19, the flow direct current machine includes a plurality of passages for the passage of gas.

21. The gas manifold of 20, wherein the plurality of passages have a length for a hydraulic diameter ratio of 5-15, or 8-12.

22. In the gas manifold of 20 or 21, the passages have a hydraulic diameter of 0.5 to 1.5 mm.

23. The gas manifold of any one of 1 to 22, further comprising a diffuser downstream of the inlet to provide a pressure drop to the gas flow.

24. A module for providing gas flow between two parallel plates of an optical component of a lithographic apparatus, wherein the module comprises a gas manifold of any one of 1 to 23 above.

25. The module of 24, further comprising an inlet portion comprising a passage of constant cross-sectional shape, between the constrictor and the outlet.

26. The module of 25, wherein the walls of the inlet portion have a thermal conductivity of at least 10 W / m / K, or at least 20 or 25 W / m / K.

27. In the module of 25 or 26, the walls of the inlet portion are made of metal.

28. The module of any one of 24 to 27, further comprising a gas source for providing gas to the inlet to be directed between two parallel plates.

29. The module of 28, wherein the gas source is a helium source.

30. The module of any one of 24 to 29, further comprising a capture device for capturing the gas exiting between the two parallel plates.

31. The module of 30, further comprising a recirculation device for providing gas captured by the capture device to the inlet.

32. A lithographic apparatus, comprising: a projection system configured to project a patterned beam of radiation onto a target portion of a substrate; Two parallel plates disposed transversely to and in the path of the radiation beam, at least one of the plates comprising a individually addressable electrical heating device configured to locally heat the plate; And a gas manifold of any one of 1 to 23 or a module of any of 24 to 31 for directing gas flow between the two parallel plates.

33. A device manufacturing method, comprising: projecting a patterned beam of radiation onto a target portion of a substrate using a projection system; Locally changing the optical path length of the radiation beam using a plate disposed transversely to and in the path of the radiation beam, the plate being locally heated; And providing the gas flow through a grating made of metal and comprising a plurality of through holes to homogenize the gas flow, between the plate and an additional plate parallel to the plate.

34. A device manufacturing method, comprising: projecting a patterned beam of radiation onto a target portion of a substrate using a projection system; Locally changing the optical path length of the radiation beam using a plate disposed transversely to and in the path of the radiation beam, the plate being locally heated; And providing the gas flow through the grating comprising a plurality of through holes in a structure with a regular period to homogenize the gas flow, between the plate and an additional plate parallel to the plate.

Claims (15)

In a gas manifold for directing gas flow between at least two parallel plates of an optical component of a lithographic apparatus,
An inlet for providing a gas flow to the gas manifold;
A lattice made of metal and comprising a plurality of through holes for homogenizing the gas flow;
A contractor disposed downstream of the lattice to reduce the cross-sectional area through which the gas flow flows; And
A gas manifold comprising an outlet disposed downstream of the systolic to provide the gas flow to the at least two parallel plates. The method of claim 1,
The through holes of the grating are regularly spaced gas manifolds. The method according to claim 1 or 2,
The grating is a gas manifold with a regular weave. A gas manifold for directing gas flow between at least two parallel plates of an optical component of a lithographic apparatus,
An inlet for providing a gas flow to the gas manifold; A lattice including a plurality of through holes in a structure having a regular period to homogenize the gas flow; A constrictor disposed downstream of the lattice to reduce the cross-sectional area through which the gas flow flows; And an outlet disposed downstream of the systolic to provide the gas flow to the at least two parallel plates. The method of claim 4, wherein
The grating has a structural integrity so that regularity is not broken by the treatment of the grating. 6. The method according to any one of claims 1 to 5,
The grating comprises at least two gratings positioned in line. The method according to claim 6,
A gas manifold that is at least as high as the aperture ratio of any downstream lattice. The method according to any one of claims 1 to 7,
And a flow direct current downstream of the inlet to straighten the flow of the gas. The method of claim 8,
The flow direct current gas is disposed upstream of the at least one grating. 10. The method according to claim 8 or 9,
The flow direct current gas manifold includes a plurality of passages for the passage of gas. 11. The method according to any one of claims 1 to 10,
And a diffuser downstream of the inlet to provide a pressure drop to the gas flow. A module for providing a gas flow between two parallel plates of an optical component of a lithographic apparatus, the module comprising the gas manifold of any one of claims 1-11. In a lithographic apparatus,
A projection system configured to project the patterned beam of radiation onto a target portion of the substrate;
Two parallel plates disposed transversely to and in the path of the radiation beam, at least one of the plates comprising a individually addressable electrical heating device configured to locally heat the plate; And
A lithographic apparatus comprising the gas manifold of any one of claims 1 to 11 or the module of claim 12 for directing gas flow between the two parallel plates. In the device manufacturing method,
Projecting the patterned beam of radiation onto a target portion of the substrate using a projection system;
Locally changing the optical path length of the radiation beam using a plate disposed transversely to and in the path of the radiation beam, the plate being locally heated; And
Providing the gas flow through a grating made of metal and comprising a plurality of through holes to homogenize the gas flow, to the constrictor and between the plate and an additional plate parallel to the plate. In the device manufacturing method,
Projecting the patterned beam of radiation onto a target portion of the substrate using a projection system;
Locally changing the optical path length of the radiation beam using a plate disposed transversely to and in the path of the radiation beam, the plate being locally heated; And
Providing the gas flow through the grating comprising a plurality of through holes in a structure having a regular period to homogenize the gas flow, to the systolic and between the plate and an additional plate parallel to the plate. Way.

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